I've been trying to figure out what makes engine noise come though my amp. Its only at idle too. Alternator is pretty new as I upgraded to a CS. The problem was there before I did that. Any thoughts?

Its feedback.... Try moving your power cable away from all other cables / wires. I always run my power cable on one side of the vehicle & my amp-input cables on the opposite. If that doesnt work you can get filters that will remove that noise.

I deal with interference on aircraft as a profession. Probably 80% of all interference problems I see are solved by improving grounding and continuity. Start with the battery and proceed through the entire electrical system. Wherever possible, loosen, clean and reconnect. Make sure there is a good, clean connection from the body of the alternator to the bracket. Upgrade wiring to a larger size, especially the main power from the battery, the wire from the alternator, the wire to the starter as well as the negative side of the battery and the ground points. You can not get more power from the battery than can travel on the negative side. It is a complete circuit.

Even if this doesn't fix your problem it will fix or improve many other things. Connected does not always mean well connected and working is not always working well.

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Steve AT 88GTP DOT com
88 GT

I had the same issues on one of my cars. The shop added additional grounds and the problem was solved.

My amps were whining like crazy. I was grounding to the console back by the PCM. I ran a wire directly from the battery ground and no more noise now.

All grounds need to be located in the same spot when using multiple amps and processors and the proper sized wire. Power lines need to be kept away from signal lines. Do not ground the chassis/case of the amps or mount them to a metal surface of the frame.

Another thing is the engine grounding straps need to be clean and attached as well.

GM uses a "floating ground" method on their cars and this can cause ground loops which will pick up noise from the ignition, lights, and/or alternator.

Thanks everyone! I have the amp grounded at one of the passenger seat rail lugs. I'm going to have to move it and see if that helps. I need to change the power wire while i'm at it too. Again thanks! +'s to those I haven't yet.

What you are experiencing is certainly not feedback and probably not interference but a ground loop. do a search on google for car stereo ground loop problem.

http://www.termpro.com/articles/noise.html is an article explaining what is happening and how to fix it or at least chase it down.

Very common problem even pros get bit by it from time to time.

nt copper spark plugs do that to?

quote Originally posted by timgray: What you are experiencing is certainly not feedback and probably not interference but a ground loop. do a search on google for car stereo ground loop problem. http://www.termpro.com/articles/noise.html is an article explaining what is happening and how to fix it or at least chase it down. Very common problem even pros get bit by it from time to time.

Awesome! Here are my problems:
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Ignition Noise
Ignition noise is another type of noise that is quite annoying. It usually sounds like a popping or buzzing sound whenever the engine is running. The best cure is to remove the motor but since we can't do that, we will have to rely on some other form of remedy. Follow the steps below to eliminate or reduce ignition noise.

Make sure you are using resistor type spark plugs and resistor type plug wires.
Determine where the noise is coming from. If the noise is a popping sound that occurs 2 or 3 times a second, you probably have a loose or bad plug wire. First, make sure that all plug wires are seated properly. If this doesn't do the trick, you may have a bad plug wire. Usually this occurs due to a pinhole in the insulation of the wire. Whenever the plug wire is energized, an arc jumps through the pinhole to the chassis of the vehicle. Replace with silicone resistor plug wires.
If the noise is a buzzing sound, the problem is usually associated with the points, distributor, or coil. Try replacing the condenser on both the coil and points. Make sure all plug wires are seated properly in the distributor cap. Additionally, you might try adding a 2200 uF cap from the positive terminal on the coil to chassis ground.
Don't use the fuse block in the vehicle to derive power for the source unit. Run the Constant Hot B+ (memory) wire directly to the battery's positive terminal.
If you still have noise, it could be occurring because of induction. Try pulling the source unit out of the dash and check for noise. If the noise is eliminated, try rerouting any wiring harnesses that are close to the deck. If this is not possible, try using self adhesive metal shielding. This might just do the trick.


Turn On/Off Thump
Turn on thump can vary from a slight pop to a mind shattering, teeth rattling BOOM! This thump is caused by the audio circuitry stabilizing when power is applied. Most amplifiers and source units have muting circuitry that lasts a couple of seconds to allow these fluctuations to subside before passing a signal. However, if the amplifier un-mutes before the source unit or any other accessory, you better watch out. Here are some things to try if you have turn on thump.

Verify that the amp has a good audio ground reference. (See rule 6 of the Ten Commandments of noise free installation.)
Don't install the system so the amplifiers can be switched on when the source unit is turned off.
If you still have thump, add a turn on delay module in line with the remote turn on wire to the amp.
This concludes the section on turn on thump.
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Good stuff. I have some wires to rerun.

[This message has been edited by ly41181 (edited 09-17-2008).]

If your grounding on the passenger side seat rail bolt, why not just pop through the firewall and ground right to the battery? It's not that much further away, unless you relocated the battery to the front spare tire well.

quote Originally posted by Khw: If your grounding on the passenger side seat rail bolt, why not just pop through the firewall and ground right to the battery? It's not that much further away, unless you relocated the battery to the front spare tire well.

Yep, the battery is up front now. But thats no big deal. I'll put the amp with the battery and run the speaker cables and rca jacks back through.

You don't say what year you car is but in the 84-87s there is an emf supressor plate on the under surface of the deck lid and one small, black ground wire to it. The clip that attatched the ground wire on my 86 GT broke off and that caused a very definate buzz in the radio that was more noticable at idle. You might check to see if your ground conection is missing to the supressor plate.

quote Originally posted by GTMN: You don't say what year you car is but in the 84-87s there is an emf supressor plate on the under surface of the deck lid and one small, black ground wire to it. The clip that attatched the ground wire on my 86 GT broke off and that caused a very definate buzz in the radio that was more noticable at idle. You might check to see if your ground conection is missing to the supressor plate.

Where is that? I have a wire that hangs free next to the relays and decklid. I have an 84 too.

quote Originally posted by ly41181: Where is that? I have a wire that hangs free next to the relays and decklid. I have an 84 too.

84's are different due to the magnisium vent. No EMF plate in them. Honestly I don't think they do much, like the metal covers around the boots of the spark plugs on the 85-88 V6 cars

Check at radio shack or a good car stereo place and see if you can get a noise filter to put on your hot wire to your amp and radio.

Nick

Noise is ulltimatly caused by spark plug wires. The reason stock/cheap wires use "suppresion core" is to suppress the noise and that is the reason they have 6,000+ ohms per foot of resitance. That is also why copper core wires can induce noise. I use Jacobs electronics spark plug wires, they have less then 200 ohms and NO radio noise. Spiral wraped stainless steel wires have low resitance and low or no noise.(which Jacobs invented) When I was into car audio my Fiero had ZERO noise, testing off a ISACA test disk. Wireing is a VERY big thing in car audio, wireing should be 1/3 of the whole system cost. Most people spend all their money on speakers and amps and buy the cheapest wire they can find. Get HIGH quality Monster Cable for the RCAs or you will get noise. Almost ALL other brands are crap. just like any amp that has a wire in it is crap, wires pick up noise. Good...errr....great amps have no wires inside of it, all suface mount. Clarion decks have a Very good feture called "zero-bit-mute-detection" that mutes the signal when no music is playing, that also helps a great deal with noise. I was trained as a sound quality judge back in the day, so I tend to get anal about car audio and high quality componets.

I still would start with the grounds and all of the above. But I highly recomend the Jacobs plug wires. More HP, more MPG, and NO noise, how can you go wrong.

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"DRIVE IT LIKE A FIERO"
'84 Fiero, engine to be determined
'87Blue GT 3.4L Swap Completed!!!!!!!! Boosted!!!!!!!
Las Vegas Fiero Club
Fiero Road Club Of Northern Nevada

[This message has been edited by sardonyx247 (edited 09-19-2008).]

Actually, I know what it is for sure now. The previous owner had a small system in the car and left the power wires, ground, and rca cables. They all run down the middle of the passenger side underneath the carpet all together and I just used them for my amp. The rca cables are picking up then engine noise from the power wire. I don't know why I didn't think of that earlier. Thanks for the help guys!

Josh